Wednesday, February 22, 2012

Driver Shaft Length and Performance



The Miles of Golf Store and Driving Range (www.milesofgolf.com) did an interesting article on driver club length and performance at http://www.milesofgolf.com/blog/golf-shafts/fitting-a-driver-for-shaft-length/

The basic premise is that the length of drivers have become increasingly longer over the years, but from what their research shows is that it does not always equate to longer distances, more clubhead speed or better overall performance. The subjects they tested were given both 45.5 inch and 44.5 inch shafted drivers.

Last July I went to the now defunct FuZion Golf center to get fitted for clubs and they stated that they have never fitted anybody for a driver over 45 inches long. It should also be noted that Bubba Watson plays a 44.75 inch driver and when I went to the PGA Merchandise Show, a PING rep told me that his driver is now 44.5 inches long. And according to Tom Wishon, he’s never seen any difference in distance between clubs that are ½” apart in distance. I tend to agree with this as well.

So why does shaft length with the driver make a difference?

I think the main reason is that if the driver is too long for a golfer they will now be standing too upright at address and this will throw off their alignments and mechanics in their swing.

Secondly, I think the MOI of the club is DRAMATICALLY affected. Unfortunately, while I really enjoy Miles of Golf’s work and recommend them for club fitting, they are still behind on the MOI fitting and matching process.


As I have discussed earlier, when I measure MOI on the GolfMechanix Auditor MOI Machine, it is measuring the amount of *force* required to swing the club. The idea behind MOI fitting is to determine the MOI of the golf club that best matches your golf swing.

Now, with the irons it’s rather simple. We can measure that by looking at the impact dispersion as we alter the weight of the *test* club.



And yes, the impact dispersion will change dramatically as you get closer to the MOI that fits you best.

However, with the driver it’s a bit different. That’s because the length of the driver is longer, so the impact dispersion will likely never be as small as it would be with a 6-iron.

With the driver the impact dispersion will get smaller (just not as small as with the iron). Thus, the secondary key to determining the best MOI for a golfer is the ball flight. Combine those two and you will find the best MOI for your driver.

Recently, PING Golf’s Dr. Paul Wood had made a comment that they did not find value in MOI matching clubs because it made the longer clubs too light. However, one has to be fit for MOI first. And, the driver has be to be fitted separately from the fairway woods which have to be fit separately from the hybrids which are fit separately from the irons. For example, here are my MOI readings for the clubs I fit myself for:

3 iron thru SW: 2,725 kg/cm^2
Hybrid (40.75” long, 18° loft): 2,765 kg/cm^2
3-wood (43.5” long, 15.5° loft): 2,785 kg/cm^2
Driver (45.25” long, 10° loft): 2,826 kg/cm^2

I’m not sure of Dr. Wood’s exact assertion or findings. But, first we must fit for MOI. MOI matching alone helps a little. But, if you’re best at 2,700 MOI and you have matched your clubs to 2,650 that means that the clubs require less of a force and effort than you put on them with your normal swing.

Using the ‘best club in the bag’ theory to MOI fit your clubs helps a little more, but it still doesn’t give the full effect. For instance, I initially used the ‘best club in the bag theory’ which was my 4-iron at 2,702 MOI. So I matched the rest of the set to that MOI. That 4-iron also had the highest MOI of my entire set of irons. But, since my optimal MOI was 2,725 I was still too light of where my clubs needed to be.

Lastly, as you can see with my clubs the MOI fitting gets higher as you go from the irons to the hybrid to the fairway wood to the driver. Thus, if a person fitted their entire set of clubs to one number, the hybrid, fairway woods and driver would be like Dr. Wood stated…too light.


So, how does this all relate back to the Miles of Golf post?

Taking an inch off the club length greatly affects the MOI which greatly affects the performance of the club for certain golfers.

A couple of days ago I installed a 69 gram UST Mamiya VTS shaft in a 203 gram Wishon 919THI driver head. When I initially trimmed the shaft, I trimmed it to 45.5 inches long. I then measured it and trimmed off a ¼” off the butt end and here’s the readings I got on the MOI machine:

45.5 inches long = 2,830 MOI
45.25 inches long = 2,775 MOI

Now, it’s apparent that Miles of Golf added some weight to the driver with the shorter shaft in order to get the swingweight heavier. Thus, I don’t believe the discrepancy in MOI between the 44.5 inch shaft and the 45.5 inch shaft was more than 100 MOI points.

However, I do believe that it could have been about 30 to 75 MOI points range, which is enough to make a difference in the performance, particularly with the driver. And as you can see, certain golfers in the Miles of Golf test had better launch conditions and better impact dispersion with one length of driver versus the other and for no rhyme or reason.

Well, there is a rhyme or reason and it really starts with the MOI of the club.






3JACK

1 comment:

Bob Sailer said...

The actual lofts of his old driver and the new driver should have been measured. The customer talked about the stamped loft on the sole like it is gospel when it is a well known fact that 99% of the time the actual loft is much higher by 1/12 or more degrees. I'd bet the farm the new driver launches lower simply because it has less loft.